The proposal is to carry out a program of research aimed at developing models of fertility, nuptiality, and mortality to serve as tools of estimation of demographic quantities from deficient and fragmentary data; to facilitate population projections; and, in general, to provide more reliable descriptions of demographic patterns and trends than is possible on the basis of raw data adjusted by use of presently existing models. The development or refinement of model life tables will progress on three main fronts. First, it will make use of international data on causes of death which were not available when the Coale and Demeny model life tables were prepared. By disaggregating and recombining, using a pattern of weights, the life tables can take on greater biological realism. Second, there will be a refinement of the very early and very late ages, in which health changes have the most immediate impact. Third, greater use will be made of Brass' linear logit transformation of standard sets of survival probabilities. Model fertility patterns are the most recent of the three types and, as is intended, can be considerably extended. There will be an effort to integrate research on birth intervals in natural fertility populations and micro-level models of fecundability, and then to bring in the role of contraception. Work so far has focused on old age mortality, an extension of nuptiality models, and on development of fertility models for first and subsequent births. In the coming year, studies of these and additional topics described above will be carried out.